Profile Luis von Ahn

In 2002, Luis von Ahn had a crazy idea: he wanted to use an
online computer game to perform the tedious task of "image
labeling," or identifying pictures and assigning them textual
descriptions. The problem with crazy ideas, of course, is that
they sound a little crazy, and so it's hard to get other people
to believe in them. Von Ahn's first paper about the game was
rejected from the ACM Conference on Human Factors in Computing
Systems [also known as "CHI"] with some of the lowest reviewing
scores possible.

Uninterested in taking "no" for an answer, von Ahn spent
several months realizing his idea as a web-based game called the
ESP Game. In the ESP Game, a player logs into a web
site and is paired up with another random player. The two players
both see the same image and are asked to write words that
describe it. As soon as the two players write the same word, they
win the round, and a new image appears. Behind the scenes, the
matched words are then used as labels for the image. In the first
four months of its operation, the ESP Game generated more
than a million labels for more than a quarter of a million
images.

His paper, now with a very significant proof-of-concept,
cruised to acceptance at the 2004 CHI conference with rave
reviews.

Experiences like this have made von Ahn accept the fact that
it sometimes takes extra work to prove everyone else wrong. Not
only do ideas like the ESP Game take months or years to
develop, but the development of those ideas requires
collaboration across many areas of computer science. When it
comes to developing games, it's not enough for the human
computation aspects to work correctly. The game has to be fun,
easy-to-use, and capable of handling potentially millions of
people trying to play simultaneously.

While the ESP Game has certainly come into its own, von
Ahn is perhaps better known for creating Captcha, a system that
helps distinguish humans from bots online, and its spin-off
ReCaptcha.

ReCaptcha works by showing people pictures of words that a
computer had trouble recognizing as text and asking people to
type it. Ticketmaster likes it because it helps ensure that the
company is interacting with a person and not a scalper's computer
program. Von Ahn likes it because, by typing in the word that
appears in a difficult-to-read image, software that he and his
team designed can reliably turn pictures of a book into words.
However, not-so-good people in the real world, like scalpers and
organized crime syndicates, want access to the resources that
ReCaptcha protects, whether free email accounts, concert tickets,
or Craigslist postings, and the results are sometimes disturbing.
While von Ahn says he's never felt threatened directly, it did
hit a little too close to home when people tried to turn off some
of ReCaptcha's servers by breaking into a Los Angeles facility
where they were stored.

In the first four months of its operation,
the ESP Game generated more than a million labels for more than a
quarter of a million images.

Von Ahn spends much of his time at Carnegie Mellon University
teaching undergraduates and advising graduate students. Teaching,
in particular, is a frequent topic on his aptly-named web site
"Luis von Blog" [http://vonahn.blogspot.com],
another place where he is unafraid of controversy.

One blog post, where von Ahn weighed the advantages of
outsourcing graduate students to third-world countries, came with
the following disclaimer: "100 percent of my PhD students are
working on projects of their own choosing." Even though they have
a well-known advisor, von Ahn says that the graduate students he
advises have not found it difficult to differentiate their work
from his. Most of them identify with different areas of computer
science and publish in different conferences.

It helps that von Ahn is uninterested in fitting into a field,
whereas many other researchers find it important to concentrate
on a particular area of computer science. The CMU professor
thinks that's just crazy, even if holding that belief implies, as
he says, that "everyone is crazy but me."

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Pointers

Acronyms

CAPTCHA

Complete Automated Public Turing test to tell Computers and Humans Apart: A contrived acronym intentionally redolent of the word “capture,” used to describe a test issued on web forms to protect against automated responses.

GWAP

Game with A Purpose: a term used to describe a computer game that layers a recreational challenge on top of a problem that demands human intelligence for efficient solution, e.g.: protein folding.

HuGS

Human-Guided Search: A research project investigating a strategy for search and optimization problems that incorporates human intuition and insight.